Mysteries Department
Sign inRequest access
0

Are the "flood tunnels" man-made?

Asked 26 Oct 2026 by ·3 answers·0·0 following
Most likely: the pit floods because it is dug below sea level into permeable, cavernous rock; no tunnel existsAhead on the evidence, not yet confirmed. It needs two reviews to be accepted.

Where it stands

Three answers have been proposed. The pit floods because it is dug below sea level into permeable, cavernous rock; no tunnel exists. leads, with evidence 2 for: supported by its tests. Two are still possible. Of the one narrower question under it, none is answered yet.

Why it matters

The engineered flood trap is the feature that turns a hole into a treasure vault, and it is the reason given for every failure since 1804. If the water is simply the island's water table in porous rock, the central claim of the legend falls⁠[1]⁠[2].

Answers 3

Evidence: 2 for
Most likely
None of these.
Not tested enough to call either way
Evidence: none yet
Still possible
Evidence: 1 for, 3 against
Disputed

History

  1. McCully puts forward: one or more tunnels were cut from Smith's Cove (and the south shore) to flood the shaft when it was breached.
  2. Nickell puts forward: the pit floods because it is dug below sea level into permeable, cavernous rock; no tunnel exists.
  3. CBC News: a 1995 Woods Hole dye study attributed the flooding to natural freshwater and tidal interaction.Against: One or more tunnels were cut from Smith's Cove (and the south shore) to flood the shaft when it was breached.
  4. Asked on this site
Add evidence
1What it bears on2What you found3Where it comes from
Which answer?
Does it count for or against it?
In a sentence, what did you find?
What you found optional
Where it comes from optional
Two reviewers check it before it counts, one of whom backs a different answer. You'll hear back by email: accepted, needs changes, or a duplicate.
Propose an answer
Your answer, in a sentence
What would rule it out? optional
Two reviewers check it before it counts, one of whom backs a different answer. You'll hear back by email: accepted, needs changes, or a duplicate.
Ask a sub-question
Your question
Why it would help optional
Two reviewers check it before it counts, one of whom backs a different answer. You'll hear back by email: accepted, needs changes, or a duplicate.
Add a source
The source
What it shows about this question optional
Two reviewers check it before it counts, one of whom backs a different answer. You'll hear back by email: accepted, needs changes, or a duplicate.

Discussion 0

Add to the discussion